As is known, integrated circuits (circuits in which all components, passive and active, are integrated on one or more substrates) are used in a variety of applications. One example application is in sensing applications in which a circuit including one or more sensing elements (e.g., pressure sensing elements, temperature sensing elements, light sensing elements, acoustic sensing elements, and magnetic field sensing elements) is used to detect one or more parameters (e.g., pressure, temperature, light, sound, magnetic field). Magnetic field sensors, for example, are circuits including one or more magnetic field sensing elements, generally in combination with other circuit components (e.g., analog, digital and/or mixed signal components), and are used to detect a magnetic field.
In motion (e.g., rotation) detectors, for example, a magnetic field sensor may be used to detect motion of an object, such as a ferromagnetic object, for example, a gear or ring magnet. A magnetic field associated with the object is typically detected by one or more magnetic field sensing elements, such as Hall effect elements and or magnetoresistance elements, which provide a signal (i.e., a magnetic field signal) proportional to a detected magnetic field. One example motion detector is described in U.S. Pat. No. 8,624,588 entitled “Apparatus and Method for Providing an Output Signal Indicative of a Speed of Rotation and a Direction of Rotation as a Ferromagnetic Object,” which is assigned to the assignee of the present disclosure and incorporated herein by reference in its entirety.
Magnetic field sensing elements and other circuitry typically have associated operational ratings and limits, or ranges of operation, such as those pertaining to temperature and magnetic field exposure. Exposure to certain conditions beyond a component's specified rating (i.e., stress conditions) during shipping, storage, and/or use may, for example, adversely affect operation of the magnetic field sensing elements and or circuitry and, thus, the reliability of a resulting device (e.g., motion detector) in which the magnetic field sensing elements and/or circuitry are provided. Whether exposure to conditions outside of a device's specified operating range damages the device depends on several factors such as the duration and/or extent of the exposure.
In high precision applications such as automobiles, accuracy in magnetic field sensing, such as may be used to detect motion of a target object, can be critical. Engine ignition timing, for example, depends on consistent detection accuracy. As one example, when magnetic field sensing elements and/or other circuitry of a magnetic field sensor integrated circuit (IC) in an engine ignition timing system are damaged due to overstress conditions, detection accuracy by the magnetic field sensor IC, and the resulting accuracy or performance of the engine ignition timing system, can be negatively impacted. Furthermore, in safety critical applications such as automobiles, compliance with standards such as Automotive Safety Integrity Level (ASIL) standards, generally requires safety mechanisms to ensure accurate and reliable circuit operation.